Netbeans seems to ignore tab size

I'm using netbeans on OpenSolaris and Solaris 10.

In a project some files ( with a extensions .tra ) were shown with wrong
tab sizes, also I do not expand tab to spaces and uses indent size 4 and tab size 4. Even changing the values didn't change anything.

Now I've changed the association of the extension to c-files and the display
is correct. In Options-Miscellaneous-Files